DEARBORN, MICH. , March 20 — Two new Ford Motor Company concept cars, the Megastar II and the Tuareg — created to commemorate the company's 75th Anniversary — were unveiled today at Ford's Design Center here.

Megastar II , based on the European Ford Taunus, was designed at the Ghia Studio of Turin, Italy, the company's international design "think-tank." Tuareg, an off-road development of the front-wheel-drive Fiesta — Ford's European success car — was created jointly by Ghia and the Dearborn Design Center.

"Although not production cars, each of these vehicles demonstrates a range of ideas and concepts which might be used on Ford cars of the future," said Eugene Bordinat, Jr., Ford vice president - Design.

As the company's 75th-Anniversary vehicles, Megastar II and Tuareg are identified with special anniversary emblems. The Megastar's name is reproduced in a unique futuristic molecular script. Ford's worldwide 75th-Anniversary observance will reach its climax June 16, the actual date of the company's incorporation in 1903.

The cars made their European debuts earlier this month at the Geneva (Switzerland) International Motor Show. At the end of this week, they will begin appearances at Auto Expo-New York, then will go to Los Angeles for the import show there.

Megastar II is a dramatic, futuristic, wedge-shaped sedan in silver and black with a contrasting orange tape-stripe scheme. The three-door five-seater is based on the Taunus two-liter Sport model. It is a direct successor to the Granada-based Megastar which toured many auto shows in Europe and the United States in 1977 and early this year.

Megastar II retains the original Taunus four-cylinder engine, four-speed transmission, front and rear suspension and aluminum road wheels. However, the overall length of the floor pan is reduced at the rear, the fuel tank is repositioned and the spare wheel is moved to the engine compartment. The front bulkhead also is moved forward and front end extended to accommodate a long chisel-shaped nose.

The all-steel-bodied Megastar II is 48.4 inches high, 68.8 inches wide and 165 inches long. The wheelbase is 101 inches.

It has a louvered, aerofoil grille. Four headlamps are recessed behind clear plastic covers and additional halogen driving lamps are located beneath the impact-absorbent front bumper. The bumper acts as an integral part of the front air dam which aids high-speed stability.

On Megastar I, only the rear window could be opened for access to the luggage area. On the Megastar II, however, the tailgate opens to the top of the inpact-absorbent rear bumper and is held open by gas-filled struts. The rear seats can be folded flat individually to provide additional luggage space.

"Teardrop"-shaped door windows can be lowered electrically, and front-hinged rear quarter windows can be opened for additional ventilation. To provide rear-seat passengers with more visibility, glass panels are built into the louvered center pillars.

The car's interior is upholstered in black leather. On either side of the center console unit, the black floor carpet includes a broad, contrasting orange stripe to reflect the exterior color scheme.

The instrument module and three-stalk control system of the Taunus are retained for Megastar II. The instruments, heater controls and radio controls are built into a single monitor unit set behind the padded four-spoke steering wheel. To prevent reflections, this monitor has a heavily tinted screen and the instruments and controls are always illuminated.

The name Megastar II is repeated on each rear-quarter panel in a new futuristic script developed from the graphic representation of a molecule.

Filippo Sapino, managing director of the Ghia Studio, said the Megastar project has paid particular attention to aerodynamics.

"The rakish design helps conserve energy and improve fuel economy and performance," he asserted.

Megastar II's small frontal area, short tail and clean lines with a minimum of external protrusions give it an efficient shape. Even the fuel filler cap has been designed with spring-loaded panels to make the hand grip flush with the bodywork to reduce drag.

Tuareg is a practical, off-road Fiesta — the popular 1978 mini-car that Ford dealers began selling in the United States last August. With sand tires, a raised suspension and an estate-car body, it is designed primarily as a desert vehicle for recreational use. A tuareg is an African nomadic tribe.

The car is based on the Fiesta Sport. Without changing the Fiesta floor pan, but by extending the roof line at the rear, designers have created a stylish but compact three-door estate car. Overall length is only 147.1 inches, width is 65.4 inches and height is 59.1 inches. The wheelbase is 90 inches.

Appropriately, Tuareg is finished in a desert beige with a contrasting orange-and-brown-stripe scheme applied to the doors, roof, hood and front.

Body design changes are purely functional. For example, to provide additional engine ventilation and cooling in desert conditions, the louvered grille is supplemented by five extra louvers built into the hood top. An enlarged aerodynamic front spoiler is extended on the sides to include wheel-arch extensions and provide running boards under the front doors.

Rollover protection is provided by a special steel hoop made integral with the roof and center pillars. A heavy-duty roof rack is intended for fuel and water containers.

Strengthened tubular steel front and rear bumper bars also are designed to be used as towing attachments. Wire-mesh grilles protect the headlamps and parking lamps, and adjustable halogen spot and search lights are mounted on the roof.

Tuareg's all-steel body has been designed with a split rear tailgate for extralong loads.

There is a fold-down rear seat and all seats are upholstered in a practical hard-wearing tweed fabric which also is used for the headlining and door and side panels. Contrasting vinyl panels are set into non-wearing surfaces. The floor and load space is protected by thick brown cord matting.

The car is powered by a 1.1-liter engine with four-speed manual transmission.